This will come as a big relief for Kolkatans: water supplied by the city’s municipal corporation is not only safe to drink but also healthy than most of the packaged variety. A study conducted by Jadavpur University’s School of Water Resources Engineering has even recommended that residents should opt for the piped water that the Kolkata Municipal Corporation (KMC) supplies for drinking purposes if it is sourced directly from the tap as this is more beneficial than mineral water.
The study was conducted last year and its findings published in the journal ‘Desalination and Water Treatment’ earlier this year. It found that KMC tap water contains more minerals required by the body for healthy living and is less acidic than many varieties of packaged drinking water (PDW) sold in the city. University researchers comprising Arunabha Majumdar, professor emeritus, Pankaj Kumar Roy, associate professor and Susanta Ray, a student, conducted the study. Majumdar is also a former director of All India Institute of Hygiene and Public Health.
They tested the quality of water of 27 mineral water brands selected randomly from different parts of the city along with 18 samples of KMC tap water collected from various parts of Kolkata.
“Under this situation of low-mineralised PDW, municipal supply water can be a good alternative for drinking. In India, bottled water is consumed primarily by people in the higher economic class group and drunk in places like social gatherings, offices, restaurants and hotels. In such circumstances, authorities should encourage people to use water supplied by the KMC,” the study said.
While the study expresses satisfaction with the quality of water when collected directly from corporation taps, it may require filtration at home if the water is storied in reservoirs where the contamination occurs.
The study said most packaged water were found with very low “total hardness (TH)” with the maximum value of 76 mg/l, “which is much below the standard limit”. It also revealed that “maximum proportion of packaged drinking water was acidic in nature.
Further, it was found that all PDW under the study contained very low concentration of TDS (total dissolved solid), TH, calcium, magnesium, chloride and other minerals. Regular consumption of very low-mineralised water may not be considered safe as it has a potential health risk for human beings. On the other hand, the quality of KMC water has been found to be good and contained all minerals with sufficient concentrations”.
Prof Majumder said the quality of water sourced from Hooghly river, after purification, is perfect for drinking, whereas the reverse osmosis system adopted by PDW manufacturers often tends to degrade the quality of water.